using System;

abstract class Puzzle {
  
  public abstract string Category{
    get;
  } 

  public abstract string PuzzlePhrase{
    get;
  } 

  public abstract int NumberOfCharsToGuess();
}   

abstract class HighScoreEntry {

  public abstract Player Player {
    get;
  } 

  public abstract int Score{
    get;
  } 
}   

abstract class Player {

  public abstract string Name{
    get;
  }

}     

abstract class PuzzleCollection {
  
  public abstract string Count{
    get;
  } 

  public abstract Puzzle this[int i]{
    get;
  }

  public abstract void Add(Puzzle p);

}   

abstract class HighScoreList {

  /* Invariant: Entries always sorted */

  public abstract void Open(string FileName);

  public abstract string Count{
    get;
  }

  public abstract HighScoreEntry this[int i]{
    get;
  } 

  public abstract void Add(HighScoreEntry e);

  public abstract void Close();

}   
  
public enum GameState {Ongoing, Won, Lost}

abstract class HangmanGame {
  /* Encapsulates the data of a single play of Hangman */

  /** Set the puzzle of this game */
  public abstract void setPuzzle(Puzzle p);

  /** Get the secret puzzle of this game */
  public abstract Puzzle CurrentPuzzle();

  /** Set the alphabet of this game - a array of all possible chars */
  public abstract void setAlphabet(char[] alphabet);

  /** Return the array of all chars not yet guessed */  
  public abstract char[] RemainingAlphabet();

  /** Return a string which represents the guessing state */
  public abstract string PuzzleOutline(Puzzle p);

  /** Call this method when the user wish to attempt ch */
  public abstract void GuessChar(char ch);

  /** Return the state of the game - Won, Lost or Ongoing */
  public abstract GameState GameState();

  /** Return the number of points obtained until now in this game */
  public abstract int HowManyPoints();

}